Is there a generic module or design concept available that I can reuse.

I wrote Tree::Parser for reasons very similar to yours. I needed to allow people to model tree-ish structures within Excel and then export them as tab-delimited files which I could parse and use. Tree::Parser is pretty flexible in terms of allowing you to build heirarchies of tree objects (the trees are Tree::Simple objects, a module I also wrote) from a variety of input styles, not just tab-delimited and even allows you to write your own custom input processors if need be. The Tree::Simple objects it produces can hold arbitrary data in their nodes as well, so there is little restriction as to the make-up of the resulting tree. Tree::Parser also supports deparsing, so its possible to easily serialize any programmatic changes back to your original files.

Let me know if you are interested in using/trying it out, and I will be happy to answer any questions you might have.